Bag bottom forming device for paper bag manufacturing machines



May 3, 1955 w I 2,707,421

BAG Bo'r'rou FORMING mzvrcr: FOR PAPER BAG MANUFACTURING MACHINES Filed-July 21, 1951 3 Sheets-Sheet 1 MARTn-1 R l'm ema Aw -91 M May 3, 1955 M. RAWE 2,707,421 ism BOTTOM roaumc; DEVICE FOR PAPER BAG ummcmmc MACHINES I 3 Sheets-Sheet} ,Filed July 21,1951

. lm errlvr: MARTIN RAME BY. Madam May 3, 1955 w 2,707,421

BAG Bo'r'rou FORMING DEVICE FOR PAPER BAG "ANUFACTURING HACHINES Filed July 21, 1951 3 Sheets-Sheet 3 Im entan' MQRTIN RAM/E nite States BAG EGTTQM FGRMENG DEVKCE FDR PAPER EAG- MAN '{JFACTURHNG MACHKNES The present invention relates to paper bag manufacturing machines and more particularly to such machines for making bags with flabbase or diamond-shaped bottoms. The principal object of this invention is to provide improved means for forming the fiat-base bottoms of such bags.

Conventional devices for bottoming flat-bags employ bow-shaped forming members traveling on chains and arranged in acute-angled position to each other, which bowshaped forming members, after having entered the preopened bottom mouth portion of a paper tube to be developed into a bag, are spread apart to form the bottom rectangle of the bag. in other lcnown devices of this kind, traveling wcdgeshaped disks are applied for folding the bottom square or rectangles. Tumbling disks arranged in slanting position in relation to the direction of travel of the paper tube have also already been proposed for forming the bottom square of a paper bag. All previously proposed and known devices, however, are more or less complicated and work satisfactorily only up to a certain still moderate of the machine and with paper tube material which is pliant and readily foldable. it higher operating "-eeds are desirable and/or when heavier paper stocks have to be applied, such known devices often cause trouble and hamper steady operation.

The present invention aims at overcoming previous difficulties and disadvantages by providing a simple folding device which gives perfect bottoming results, also when working heavy, stiff, and even corrugated paper stock material, and allows higher operation and production speeds by troubledree operation. in the form of this device disclosed herein, the portion of a flattened paper tube, folded and pasted from a paper web in a previous operation, destined to form the bag bottom is bent in a known manner at right angle toward one flat side of the tube and passed between oppositely arranged suction nozzles which pre-open the mouth of the tube; whereupon said mouth is further expanded by a rotating spreader finger or the like. Then both side flaps are almost flattened down in opposite directions by oppositely arranged bow shaped forming members, and finally the paper tube with its so prepared bottom portion is fed into a device according to the invention which successively forms first the leading bottom portion and then the trailing bottom portion before the flat-base bottom is completed by subsequent mechanisms.

More specifically stated, the forming device of the present invention comprises subsequent to known, means for opening and flattening down the side flaps of a paper tube end portion from which the bag bottom is to be formed, a device for squaring and forming first the leading and then the trailing portion of the bottom while the paper tube is moving transversely to its longitudinal axis. The means for forming the bottom square portions comprise two pairs of folding fingers pivotally mounted with their actuating means on traveling carriers which, during their travel, subject the folding fingers to swinging motions in a horizontal plane, whereby the latter suitably atet Fatented May 3, i955 "ice enter the leading and the trailing bottom portion of the paper bag and form thereby the bottom of the bag.

A feature of this invention, believed to be novel, is the manner in which the swinging cyclic motion of the pairs of folding fingers is obtained. For this purpose the folding fingers, one of a pair on one side and the other on the opposite side of the path traveled by the paper tube, are integral parts of crank levers pivotally mounted on the traveling carriers and provided with guide rollers at their free ends engaging guide ways of suitable curvature to effect the desired swinging movements of the folding fingers in a horizontal plane.

Another feature of this invention is the construction of the traveiing carriers on which the crank levers with folding fingers are pivotally mounted and which comprise pairs of chains or belts, one pair at each side of the path traveled by the paper tube, trained over sprockets or pulleys and arranged parallel to the guide ways which the guide rollers of the crank levers engage.

Another feature of this invention is the arrangement and operation of the crank levers of which the folding fingers form an integral part and which are pivotally mounted on the travelling carriers in such a manner that the free ends of the leading levers point forward and, the free ends of the trailing levers point backward, resulting in that the leading folding fingers swing in 0pposite direction to the trailing fingers when the levers with their guide rollers pass the same curvature in the guide ways. Thus, all folding fingers swing outwardly relative to a center point of the bottom square for forming the bottom of the bag.

Still another feature of this invention resides in novel adjusting means for the bottom squaring and forming device which are simple in construction and allow quick change-over from one bottom-rectangle proportion to another one, or from one tube size to another by changing the distance between the guide ways and/or the distance between the leading and the trailing pairs of folding fingers. To facilitate the latter change, the leading pair of folding fingers with their operating cranks is mounted on a di 'erent set of travelling carriers as the trailing pair; thus simple adjustment of the space etween the leading and trailing folding finger units will be obtained by varying the relative position of the driving sprockets or pulleys of the two sets of travelling carriers to each other.

Further advantages and features of this invention will become apparent from the following detailed description of a preferred embodiment when taken in connection with the accompanying drawings in which Fig. 1 shows the whole bag bottom forming device in longitudinal section on the line l-I of Fig. 2,

Fig. 2 shows a view of the same bag bottom forming device from above,

Fig. 3 is a vertical section on the line IlI-III of Fig. 1,

Fig. 4- is a vertical section on the line IV-IV of Fig. 1,

Fig. 5 shows the means for pro-opening of the bottom portion of the fastened paper tube in a vertical planview opposite to the direction of movement of the paper tube.

Referring to the drawings, a flattened paper tube 1 with bottom portion 2 bent at substantially right angle toward one flat side of the tube is fed to pass with said bottom portion 2 between suction nozzles 3 which preopen the mouth of the tube at this bottom end. Immediately thereafter, the spreader finger 4, rotating with a horizontal shaft, enters the mouth, expands it still further, and keeps it open until oppositely arranged. bow-shaped forming members 5 engage this tube portion and almost flatten down both side flaps in opposite directions into a substantially horizontal plane. With the bottom flaps in this position, the paper tube 1 is carried sideward in the direction of the arrow to a station in which, during continued travel, the devices for forming the bottom square is operating. The mechanism for conveying the paper tube to pass the several stations may be of any customary construction and as, being no part of this invention, need not be described or illustrated here.

The forming members 5, rotating in opposite directions, are driven by bevel gears 26 whereas the suction nozzles 3 are driven by bevel gears 27; and the rotating spreader finger 4 is driven by a horizontal shaft 28. The suction nozzles are mounted on spindle 29 which is provided with an axial suction duct 30.

The device for forming the bottom square or rectangle of the paper bag according to this invention comprises substantially a frame 6 carrying shafts 7 and S in spaced parallel relation on which pairs of sprockets or pulleys 9-9 and 1010 are mounted. Said sprockets or pulleys serve to accommodate two pairs of endless chains or belts 11-11 and 1212 which are so arranged that the belts of pair 1111 and of pair 1212 travel parallel and adjacent to each other but that a certain pre-determined distance is maintained between the two pairs, as can best be seen in Fig. 2. Pivotally mounted at pre-determined points of chains or belts 11 and 12 are pairs of folding fingers 13-13 and 14-14 which are integral parts of crank levers 1515 and 1616, which in turn carry guide rollers 17 on their outer ends. Said guide rollers engage guide ways 18 provided in guide rails 19 which are arranged adjacent and parallel to the pairs of belts 11-11 and 12-12. It will be seen in Fig. 2 that the endless chains or belts, trained over the sprockets or pulleys 9 and 10, form a straight upper and a returning lower strand. The upper strand enters and extends parallel to the path taken by the paper tube or bag being constructed. It will further be noted in Fig. 1 that the guide ways 18 have outwardly curved portions 20 at the beginning and inwardly curved portions 21 at the ending of the intermediate upper horizontal portions throughout which the guide ways run straight and parallel to each other and also to the upper strands of the chains or belts 11 and 12. The curved portions 20 and 21 of the guide ways perform an important function in the operation of the device of this invention in that they impart swinging motions to the folding fingers 13, 14, whenever guide rollers 17 pass said portions. This is because each crank lever 15 or 16, each of them carrying a guide roller 17, is an integral part of its respective folding fingers 13 or 14, and because these units 13--15, 1416 swing about their pivot points fixed to and traveling with chain or belt 11, 12. The curved portions 20, 21 of the guide ways 18 are formed in such fashion that an angular motion of substantially 45. degrees is imparted to a folding'finger unit whenever its guide rollers 17 passes such a portion.

The location of the outwardly curved portions 20 relative to the traveling folding fingers and the traveling paper tube bottom portion 2 is such that said folding fingers are actuated for engagement with said bottom portion at the beginning of the straight upper strand; and, correspondingly, the location of the inwardly curved portions 21, is such that said folding fingers are actuated for disengagement at the ending of said strand. Referring to Fig. 2, it will be noted that the crank levers 15, leading in the direction of operative travel, have their pivot points at their rear ends and the crank levers 16, trailing in the direction of operative travel, have their pivot points at their front ends. Thus, the leading folding fingers 13, being integral parts of crank levers 15, perform a forward swinging motion when the guide rollers 17, carried on the free front end of levers 15, pass the outwardly curved portions 20; and the trailing fingers 14, being integral parts of crank levers 16,

perform a backward swinging motion when the guide roller 17, carried on the free rear end of levers 16, pass the inwardly curved portions 21 of guide ways 13, as will be understood by referring to Fig. 2. Moreover, it will be clear by reference to the Fig. 2 that the swinging motions of all crank levers and their folding fingers effected by curves 21 will be in opposite direction to the motions effected by curves 20, since the curvatures are correspondingly inclined. Thus, both pairs of folding fingers (the leading and the trailing pair), extending transversely of the direction of operative travel during the remaining part of their Way, as indicated in dotted lines, in Fig. 2, swing outwardly relative to a common center point into a diamond con figuration when passing the outward curves 20, will remain in this position during their travel along the upper intermediate straight portion of the guide ways, and will recede into their transverse position when passing the inward curves 21. Since these swinging movements of the folding fingers are timed in proper relation with the conveying movement of the paper tube in such a manner that the outward-swinging motion occurs at the instant of engagement of the paper tube with the folding fingers and the receding motion, at the instant of disengagement, the folding fingers enter into the opened flaps of the paper tube bottom portion, pull them in shape, and form the folds and creases of the bottom portions of a paper bag.

The proper position of the pairs of traveling carriers, comprising the chains or belts 11, 12, for the folding finger units 14--16, and 1517, and the appertaining guide rails 19 with guide ways 18, is secured by means of crossties 31 interposed between the longitudinal side beams 6 and by distance sleeves inserted between guide rails 19 and said beams. When othertypes of paper bags have to be fabricated and adjustment for other paper tube sizes is necessary, such adjustment can readily be made by unscrewing the fastening means of shafts 7, 8 and by exchanging distance sleeves 24 for such of suitable length. As already referred to, the pairs of folding fingers 1313, 1414 swing outwardly at the instant the paper tube bottom portion 2 advances into engagement with them and recede at the instant of disengagement. By this action, the leading pair of folding fingers 13 operates first and forms the leading bottom square portion 22, and the trailing pair of folding fingers 14 operate second and forms the trailing bottom square portion 23. For a certain time, however, both pairs of folding fingers 13-13, 14-14 to operate simultaneously on bottom portion 2 and so assure that perfectly creased folds and positive formings of the bottom square portions are obtained even if heavy, stiff or corrugated paper is used.

Since the folding members and the paper tube from t which the bags are to be fabricated travel in the same direction and at the same rate of speed during the bottoming operation, the operating speed of the machine can be considerably accelerated and can be much higher than in conventional paper bag machines. After forming the bottom square or rectangle 22, 23, according to the method of this invention, the semi-finished bag passes on to devices for finishing the bottom of the bag. Since any of such devices which are generally known in the art can be employed, they form no part of this invention and need not be described here.

For further facilitating of the adjustment of the present device when it has to be adapted for the manufacturing of bags of different size, means have been provided by which the distance between the leading and trailing pairs of folding finger units can be changed. To make such change quickly and conveniently possible, the traveling carriers for the folding finger units, comprising chains or belts 11 and 12, are provided in pairs as has already been stated. So the leading folding finger units 13, 15 are pivotally secured to a carrier being connected to the inner chains or belts 11, 12 and the trailing folding finger units 14, 16 to the outer chains or belts 11, 12. In the embodiment shown in the drawing, the chains or belts to which the leading folding finger units are secured to the traveling carriers nearest to the path of the paper tube; whereas the trailing pair of folding finger units 14, 16 is pivotally secured to the outer chains or belts 11, 12 correspondingly. Now it will be understood that to change the distance between the leading and trailing pair of folding fingers, it is only necessary to change the relative position of the chains or belts 11 and 12, which can best be accomplished by shifting the adjacent carryingsprockets or pulleys 9, 10 relatively to each other. For this reason the sprockets or pulleys of a pair are secured to each other by means of screws 32 and slotted holes which make such adjustment readily possible.

The endless chains or belts 11, 12 of the devices are driven from a suitable power drive (not illustrated) acting on spur gear or pulley 25 mounted on shaft 7.

Having thus described a preferred embodiment of my present invention in full detail, I am aware that various changes may be made in certain details of the construction illustrated and therefore I do not wish to be limited except as defined by the scope and spirit of the appended claims.

What I claim is:

l. A device of the character described comprising a frame, two shafts mounted in spaced parallel relation in said frame, pulleys secured to said shafts, two pairs of endless carrier means trained over said pulleys and extending in upper and lower strands from one of said shafts to the other, one pair of said carrier means arranged toward one lateral side of said frame and the other pair toward the opposite side thereof and both pairs of said carrier means being adapted to travel in longitudinal direction of the frame, guide ways arranged toward the inside of and parallel to each pair of carrier means, two pairs of folding finger units mounted to pivot in a horizontal plane being arranged in rectangular configuration on said carrier means of which one pair is leading and the other trailing relative to the direction of travel of said carrier means, said folding finger units being adapted to engage the bottom inside portion of paper tubes moving in the same direction and at the same speed as said carrier means, each of said folding finger units including a crank lever extending radially from its pivot point and a guide roller carried by said crank lever at its outer end adapted to engage said guide ways, said crank levers of the leading pair of units extending in opposite direction to said crank levers of the trailing pair of units.

2. A device as per claim 1, in which at least one pair of oppositely arranged folding finger units is adjustably mounted on its carriers of said pair of carrier means in the direction of travel of said carrier means for enabling changement of the space between the leading and trailing pairs of folding finger units.

3. In an automatic bag bottom forming machine comprising bag tube feeding means adapted to feed the bag tubes in longitudinal position to the machine, means for pre-opening the bottom portion of the flat paper tube consisting of means for flattening down in opposite directions the side flaps of the paper tube bottom portion, and subsequent means for conveying said paper bag with opened bottom portion in transverse direction to its axis, a device for bag bottom squaring by forming subsequently first the leading and then the trailing bottom portion of said bag tube bottom being disposed in the Way of the transversely moved bag tube, cooperating with said bag tube conveying means and consisting of pairs of folding finger units, means for carrying and moving said pairs of folding finger units along endless path partly intersecting the path of said bag tube actuating means for said folding finger units imparting swinging motions to the folding finger-units in the plane of the paper tubes during their bag tubes and during their travel along the upper part of said endless path.

4. In an automatic bag bottom forming machine a device for bag bottom squaring by moving the bag tubes with their opened bottom ends in transverse direction to its axis and forming subsequently first the leading and then the trailing bottom portion of said paper tube during its movement, comprising conveying means for the bag tubes, pairs of folding finger units, carrier means for moving said pairs of folding finger units along an endless path in cooperation with said bag tube conveying means, said folding finger units being pivotally mounted in pairs oppositely to each other on said carrier means to pivot in the plane of the bag tubes and their motion, each of said folding finger units consisting of a folding finger, a crank lever integrally fixed with one end to said folding finger at the pivot point of said folding finger unit and a guide roller pivotally arranged at the other end of said crank lever; and stationary guide ways for said guide rollers for imparting swinging motion to the folding fingers in the plane of the bag tubes and their motion for their engagement with the inside bottom portions of the paper tubes during their travel along the upper part of said continuous path.

5. In an automatic bag bottom forming machine a device for bag bottom squaring by moving the bag tubes with their opened bottom ends in transverse direction to its axis and forming subsequently first the leading and then the trailing bottom portion of said paper tube during its movement, comprising conveying means for the bag tubes, pairs of folding finger units, carrier means for moving said pairs of folding fingers units along an endless path in cooperation with said bag tube conveying means, said folding finger units being pivotally mounted in pairs oppositely to each other on said carrier means to pivot in the plane of the bag tubes and their motion, each of said folding finger units consisting of a folding finger, a crank lever integrally fixed with one end to said folding finger at the pivot point of said folding finger unit and a guide roller pivotally arranged at the other end of said crank lever; and stationary guide ways for said guide rollers for imparting swinging motion to the folding fingers in the plane of the bag tubes and their motion for their engagement with the inside bottom portions of the paper tubes during their travel along the upper part of said continuous path, said carrier means for said folding finger units constitute endless flexible string-like means being trained over rotatable means and arranged adjacent and parallel to said stationary guide ways for the guide rollers of said folding finger units.

6. In an automatic bag bottom forming machine a device for bag bottom squaring by moving the bag tubes with their opened bottom ends in transverse direction to its axis and forming subsequently first the leading and then the trailing bottom portion of said paper tube during its movement, comprising conveying means for the bag tubes, pairs of folding finger units, carrier means for moving said pairs of folding finger units along an endless path in cooperation with said bag tube conveying means, said foldmg finger units being pivotally mounted in pairs oppositely to each other on said carrier means to pivot 1n the plane of the bag tubes and their motion, each of said folding finger units consisting of a folding finger, a crank lever integrally fixed with one end to said folding finger at the pivot point of said folding finger unit and a guide roller pivotally arranged at the other end of said crank lever; and stationary guide ways for said guide rollers for imparting swinging motion to the folding fingers in the plane of the bag tubes and their motion for their engagement with the inside bottom portions of the travel along the upper part of said continuous path, said carrier means for said folding finger units constitute endless flexible string-like means movably arranged to said guide ways for the guide rollers of said folding finger units the upper straight portion of said stationary guide ways coinciding with the path travelled by the paper tube bottom portions during their engagement with said folding fingers.

7. In an automatic bag bottom forming machine a device for bag bottom squaring by moving the bag tubes with their opened bottom ends in transverse direction to its axis and forming subsequently first the leading and then the trailing bottom portion of said paper tube during its movement, comprising conveying means for the bag tubes, pairs of folding finger units, carrier means for moving said pairs of folding finger units along an endless path in cooperation with said bag tube conveying means, said folding finger units being pivotally mounted in pairs oppositely to each other on said carrier means to pivot in the plane of the bag tubes and their motion, each of said folding finger units consisting of a folding finger, a crank lever integrally fixed with one end to said folding finger at the pivot point of said folding finger unit and a guide roller pivotally arranged at the other end of said crank lever; and stationary guide ways for said guide rollers for imparting swinging motion to the folding fingers in the plane of the bag tubes and their motion for their engagement Withthe inside bottom portions of the paper tubes during their travel along the upper part of said continuous path, said guide ways for the guide rollers of said folding finger units having outwardly curved portions at the beginning and inwardly curved portions at the ending of their intermediate upper straight portion coinciding with the path travelled by the paper tube bottom portions, said outwardly curved portions being adapted to swing the folding fingers by means of said guide rollers and crank levers into engagement with the inside bottom portion of the paper tube, and said inwardly curved portions being adapted to swing the folding fingers analogously out of engagement with the inside bottom portion of the paper tube.

8. A device as per claim 1, in which one pair of said oppositely arranged folding finger units is pivotally mounted on the inner carriers of said two pairs of carrier means and the other pair of oppositely arranged folding finger units is pivotally mounted on the outer carriers of said two pairs of carrier means, and in which the adja-' cent pulleys of'a pair of carrier means are angularly adjustable to each otherin order to make relative adjustment of the endless carrier means and of the spaced relation between the leading and trailing pairs of folding finger units in the direction of travel of the paper tube possible.

References Cited in the file of this patent UNITED STATES PATENTS 661,330 Westervelt Nov. 6, 1900 925,296 Claussen June 15, 1909 2,202,431 Rohrbacker May 28, 1940 2,224,656 Robinson Dec. 10, 1940 2,570,047 Burroughs Oct. 2, 1951 FOREIGN PATENTS 640,287 Germany Dec. 29, 1936 

